Semi-packed DNA: One Chromosome

1
Semi-packed DNA One Chromosome
2
DNA Packing
3
RNA Structure

• Single-stranded polymer of ribonucleotides
• Can be double-stranded (viral genome), no helix
• Can form DNA-RNA hybrid helices
• Can form hairpins, loops, double-stranded
  regions, etc.
• Similar to DNA
• Directionality - 5 to 3
• Backbone (sugar is ribose, not 2-deoxyribose)
• Four nucleotides (A, G, C, U)
• Types mRNA, hnRNA, tRNA, rRNA, etc.

4
mRNA/tRNA Function

• mRNA
• Intermediary between DNA (storage) and
  translation (protein production)
• Modified (in eukaryotes) before translation
• 5-methylated cap
• Splicing
• 3-polyadenylation
• tRNA
• Must be amino-acylated before functional
• Translator molecule between mRNA and amino acids

5
mRNA Secondary Structure 3UTR of bicoid
(Drosophila)
6
General tRNA Structure - A Cloverleaf
Amino-acylation
Amino-acylation
7
3-D Structure of tRNA
8
Homework

• Complement the ssDNA below, then draw the
  chemical structure of the resulting dsDNA
  molecule. Label the 5 and 3 terminus of each
  strand, each base, and show the hydrogen bonds
  between each base pair (see handout)
• 5 - ATCG - 3
• Given the following template strand of DNA, a)
  Provide the complemented dsDNA, label template,
  non-template, coding and non-coding strands, b)
  Transcribe the DNA into mRNA, label the 5 and 3
  terminus c) Translate the mRNA into protein
  sequence, label the amino and carboxy terminus
• 5 - TACCTCGGATTTCGCATC - 3